Change the properties dialog response to
GTK_RESPONSE_CANCEL instead of GTK_RESPONSE_CLOSE. This
will make the dialog go away when the user presses
enter. With gtk+ >= 2.9 this will happen anyway, but for
older gtk+ versions only GTK_RESPONSE_CANCEL is bound to
escape by default. Fixes bug #340539. See also bug
#101293 for the gtk+ part.